Foreword

The Intergovernmental Panel on Climate Change (IPCC) was jointly established
by the World Meteorological Organization (WMO) and the United Nations Environment
Programme (UNEP) in 1988. Its terms of reference include (i) to assess available
scientific and socio-economic information on climate change and its impacts
and on the options for mitigating climate change and adapting to it and (ii)
to provide, on request, scientific/technical/socio-economic advice to the Conference
of the Parties (COP) to the United Nations Framework Convention on Climate Change
(UNFCCC). From 1990, the IPCC has produced a series of Assessment Reports, Special
Reports, Technical Papers, methodologies and other products that have become
standard works of reference, widely used by policymakers, scientists and other
experts.

This volume, which forms part of the Third Assessment Report (TAR), has been
produced by Working Group I (WGI) of the IPCC and focuses on the science of
climate change. It consists of 14 chapters covering the physical climate system,
the factors that drive climate change, analyses of past climate and projections
of future climate change, and detection and attribution of human influences
on recent climate.

As is usual in the IPCC, success in producing this report has depended first
and foremost on the knowledge, enthusiasm and co-operation of many hundreds
of experts worldwide, in many related but different disciplines. We would like
to express our gratitude to all the Co-ordinating Lead Authors, Lead Authors,
Contributing Authors, Review Editors and Reviewers. These individuals have devoted
enormous time and effort to produce this report and we are extremely grateful
for their commitment to the IPCC process. We would like to thank the staff of
the WGI Technical Support Unit and the IPCC Secretariat for their dedication
in co-ordinating the production of another successful IPCC report. We are also
grateful to the governments, who have supported their scientists' participation
in the IPCC process and who have contributed to the IPCC Trust Fund to provide
for the essential participation of experts from developing countries and countries
with economies in transition. We would like to express our appreciation to the
governments of France, Tanzania, New Zealand and Canada who hosted drafting
sessions in their countries, to the government of China, who hosted the final
session of Working Group I in Shanghai, and to the government of the United
Kingdom, who funded the WGI Technical Support Unit.

We would particularly like to thank Dr Robert Watson, Chairman of the IPCC,
for his sound direction and tireless and able guidance of the IPCC, and Sir
John Houghton and Prof. Ding Yihui, the Co-Chairmen of Working Group I, for
their skillful leadership of Working Group I through the production of this
report.